using (DbCommand command = connection.CreateCommand())
{
//Create a directory based on the Spreadsheet name to store the csv versions of the worksheets
string newDirectory = _fileNameandPath.Remove(_fileNameandPath.LastIndexOf("."));
if (!Directory.Exists(newDirectory))
Directory.CreateDirectory(newDirectory);
foreach (string workSheetName in _workSheets)
{
//Create a csv file for this worksheet
StreamWriter sw = File.CreateText(newDirectory + "\\" + workSheetName + ".csv"); 
// Worksheets are referenced by their worksheet names
// We require all rows from the worksheet
command.CommandText = "SELECT * FROM [" + workSheetName + "$]";
if (connection.State != ConnectionState.Open)
connection.Open();
StringBuilder dataLine = new StringBuilder();
//Populate the DataReader with data from the worksheet
using (DbDataReader dr = command.ExecuteReader())
{
while (dr.Read())
{
//Reset the string builder
dataLine.Remove(0, dataLine.Length);
//Build comma delimited string
for (int fieldCount = 0; i < dr.FieldCount; i++)
{
dataLine.Append(dr[fieldCount]);
//Exclude trailing comma from final field
if(fieldCount  != dr.FieldCount - 1)
dataLine.Append(",");
}
sw.WriteLine(dataLine);
}
sw.Close();
}
}
}

dataLine.Append(dr[fieldCount]);

dataLine.Append("\"" + dr[fieldCount] + "\"");